A thin film transistor liquid crystal display (TFT-LCD) is a variant of liquid crystal display (LCD) which uses thin film transistor (TFT) technology to improve image quality. With recent interests and development, an organic light-emitting diode (OLED) device has become a potential candidate to replace LCDs for next-generation display. Depending on the direction of output light, the TFT-LCD devices are generally classified into three types, i.e. a transmissive LCD, a reflective LCD, and a transflective LCD. Whereas, the OLED devices are generally classified into two types, i.e. a bottom emission OLED device and a top emission OLED device. In the reflective LCD and the transflective LCD, a reflective layer with a high reflectivity is disposed under the glass substrate for reflecting the ambient light so as to light up the whole LCD. The top emission OLED device uses an anode electrode as a reflective layer. When a current passes through the light-emitting material layer of the top emission OLED device, the light emitted from the top emission OLED device is reflected by the anode electrode (reflective layer) so as to achieve the purpose of top emission.
Conventionally, the highly reflective metallic material used in the reflective layer includes for example silver (Ag), aluminum (Al), platinum (Pt), and so on. During production of the top emission OLED device, the highly reflective metallic material is readily exfoliated by the acidic/basic action of the etchant solution and thus the emission quality and efficiency is impaired. For solving such a problem, a reflective layer having a multi-layered structure is proposed. In the multi-layered structure, a highly reflective metallic material layer is sandwiched between conductive oxide material layers such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) so as to protect the highly reflective metallic material layer during production. The process of forming the multi-layered structure of the reflective layer is disclosed in for example U.S. Pat. No. 7,224,115 and U.S. Pat. No. 7,190,111 and US Patent Publication Nos. US2006/0049747 and US2006/0243976.
FIG. 1 is a cross-sectional view of an OLED device having a multi-layered anode structure disclosed in U.S. Pat. No. 7,224,115. As shown in FIG. 1, the OLED device comprises an anode layer 10, a hole transport layer 11, an emission layer 12, an electron transport layer 13, a hole injection layer 14, a cathode layer 15, a planarization layer 16, an insulator layer 17, a via hole 18 and a gate electrode 19. The anode layer 10 is a three-layered structure including a first anode 101, a second anode 102 and a third anode 103. The first anode 101 is made of highly reflective metallic material such as silver (Ag), aluminum (Al) or Ag/Al alloy. The second anode 102 and the third anode 103 are made of conductive oxide material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). Although the multi-layered anode structure is capable of protecting the highly reflective metallic material from being attacked during production, there are still some drawbacks. For example, since the second anode 102 and the third anode 103 can only protect the top surface and the bottom surface of the first anode 101, the periphery of the first anode 101 is possibly etched and exfoliated on account of occasional reasons.
Therefore, there is a need of providing an active matrix display having a sidewall-protective structure for protecting the anode reflective layer to obviate the drawbacks encountered from the prior art.